Refers to the aching, burning feeling that begins in the chest and settles in the stomach/core when one is experiencing the come down after taking molly. Often accompanied by various other symptoms, like a distinct loss of energy, muscle aches, and jaw soreness.

Jaden - "What does molly cave feel like?"
RP - "Imagine a cut open geode stone in your abdomen filled with crystals of molly that sucks out all the nutrients and good-feeling from your body and makes you wonder how the fuck you somehow forget this part every time."
Jaden - "...Oh."